 #define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main()
{
	double hig = 0;
	double sum = 0;
	double avg = 0;
	int i = 0;
	for (i = 0; i < 5; i++)
	{
		scanf("%lf", &hig);
		sum += hig;
		avg = sum / 5;
	}
	printf("%.2lf", avg);
	return 0;
}